As a hybrid circuit configured by a high-voltage circuit and a low-voltage circuit having different power supply voltages, respectively, there have been proposed hybrid circuits disclosed in JP-A-11-176479 (PTL 1) and JP-A-2006-009687 (PTL 2). In each of the patent literatures, the high-voltage circuit and the low-voltage circuit are mounted on different boards and are disposed so as to be laminated to each other thereby suppressing the increase of the disposing area of the boards.